Electrical traffic analysers



July 11, 1961 L. J. ROBSON 2,991,935

ELECTRICAL TRAFFIC ANALYSERS Filed March 4, 1958 8 Sheets-Sheet 1 L. J.RoBsoN 2,991,935 ELECTRICAL TRAFFIC ANALYsERs 8 Sheets-Sheet 2 July 11,1961 Filed March 4, 1958 llzz/zjezzai July 11, 1961 J. RoBsoN ELECTRICALTRAFFIC ANALYsERs 8 Sheets-Sheet 3 Filed March 4, 1958 July 11, 1961 LJ, RQBSON 2,991,935

ELECTRICAL TRAFFIC ANALYSERS FiledlMaroh 4. 1958 8 Sheets-Sheet 4 Julyll, 1961 ..1.RoEsscJN ELECTRICAL TRAFFIC ANALYSERS 8 Sheets-Sheet 5Filed March 4, 1958 con n lf2/061x501* ZL Jo Z2@ 017/ EE w @l a m WMWIMUJuly 11, 1961 L J, ROBSON 2,991,935

ELECTRICAL TRAFFIC ANALYSERS Filed March 4, 1958 8 Sheets-Sheet 6 DDM lIII-I j@ 4 July 11, 1961 J. ROBSON ELECTRICAL TRAFFIC ANALYSERS 8Sheets-Sheet 7 FiledMarch 4, 1958 @imm SMT/1.

m im? AEXEXV XBV 8 Sheets-Sheet 8 Filed March 4, 1958 W NQL @NME UnitedStates Patent O 2,991,935 ELECTRICAL TRAFFIC ANALYSERS Leslie JohnRobson, London, England, assigner to Automatic Switching Limited,London, England Filed Mar. 4, 1958, Ser. No. 719,052 Claims priority,application Great Britain Mar. 8, 1957 2 Claims. (Cl. 23S-92) Thepresent invention relates to a circuit arrangement suitable for theautomatic recording of utilization e.g. the total circuit utilizationtime and the number of messages completed in specific selected periodsof time simultaneously over two or more radio, telegraph or telephonecircuits.

The invention consists of an yarrangement for recording the utilizatione.g. of a signal channel comprising an electrical pulse drive, a pulsecounter and means for connecting the pulse drive to operate or not tooperate the counter in accordance with the utilization condition.

The invention further consists of an arrangement for recordingutilization e.g. of a signal channel by means of an electrical pulsedrive, comprising a plurality of pulse counters, a sequence switchadapted to be connected in succession to individual counters, means todetect the particular utilization, means for connecting the pulse driveto the sequence switch to operate or not to operate the counterconnected thereto for each pulse of the drive in accordance with theutilization indication detected and a counting unit connected to stepthe sequence switch to its next position after a predetermined number ofpulses have been counted.

Conveniently, the utilization of a plurality of signal channels can besimultaneously recorded.

By utilization of a channel is meant the period during which a channelis in use or operative or the number of times in which the channel is inuse or operative in a given period and possibly the length of eachperiod of use or operation or both.

Means may be provided whereby the period between successive steps of thesequence switch may be varied.

Pulses may also be extended to operate a camera to photograph theelectro-magnetic counter readings at intervals of time.

The arrangement may then be adapted for continuous recording i.e.without the need for periodic reading of the counters and manualresetting.

Alternatively recording may be eifected by printing.

The arrangement will be further described with reference -to embodimentsfor recording the circuit utilization time and/or message count of theradio, telegraph or telephone traffic shown in the accompanyingdrawings.

FIGURE l shows the circuit diagram for a circuit utilization unit withcircuit utilization and/or message count displayed on counters requiringmanual transcription.

FIGURES 2 Iand 2a show the circuit diagram of an alternative circuitutilization unit recording the utilization and/ or message count and/ orthe total length of each message transcribed automatically on to acontinuous printed paper roll, tape or other means of permanent record.

FIGURE 3 is a side elevation and FIGURE 4 is a plan of three of themeters of FIG- URES 2 and 2a.

FIGURE 5 shows the circuit diagram of a period selection and counterunit.

FIGURE 6 shows the circut diagram of an alternative part sectionalcounter unit.

FIGURES 7 and 7a show the circuit diagram of a further circuitutilization unit.

In the embodiment to be described the circuit utilization time wouldnormally be recorded in seconds derived from an inherent one-secondpulse circuit or from an external impulse or master clock system. Othertiming intervals, however, may be used.

The facilities provided by the equipment are as follows.

(l) The recording in seconds (or any other unit of time) ofthe circuitutilization time of each of one or more radio, telegraph or telephonecircuits.

(2) The recording in seconds (or any other unit of time) of the circuitutilization time of each of one or more radio, telegraph or telephonecircuits plus the number of messages completed of each.

(3) The recording in seconds (or any other unit of time) of the circuitutilization time of each of one or more radio, telegraph or telephonecircuits plus the number of messages completed plus the utilization timeof each message.

In the following the designations P, TP, VA, RVA etc. are referred to inthe specification with the prefix relay. The drawing shows such elementsas scription as M or C but are ampljied again in the circuit diagram asM25 C25 a or T as the case may be. These additional symbols denote thenumber of bank contacts successively stepped by the uniselectors as thewipers traverse the banks (i.e. in the cases quoted 25) and denote alsothat each has four such rows of bank contacts.`

The wipers traversing each row of bank contacts are thereby shown tototal 4 also and step simultaneously from contact to contact i.e. whenthe wiper of one bank contact is on contact 11, the other three wipersare like- Wise also on their bank contact 11.

In FIGURE l there is shown terminals BT designated Battery Terminal towhich connection is made by plug and cord connection to a 50 volt and150 volt D.C. source of supply, the negative terminals of which arecommoned to earth.

A jack PJ designated one-second pulse jack to which connection is madeby plug and cord to a one-second D.C. pulse source of supply if derivedfrom an external source.

The inherent one-second pulse circuit compris-ing the cold cathode tubeand pulsing relay P may be used, in which case operation of the batteryon/oi switch to the On position will extend an ear-th condition at onesecond intervals via P2 contact PI (with no plug inserted) to pulserelay TP at one-second intervals. This condition is referred to as apulsing earth.

A lamp jack BPL designated battery and pulse lamp to indicate that thebattery is connected and that the equipment is receiving the train ofincoming one-second pulses. This condition will be indicated by relay TPpulsing at one-second intervals and flashing lamp BPL via its pulsingcontact TF1.

Six jacks AJ, BI, CI, DI, E] and FI (with associated lamp jacks A, B, C,D, E and F) designated circuit jacks to which connection is made by plugand cord to` the equipment monitor jacks of the circuits underinvestigation. Each of these circuit jacks is connected via an ampliiierdetector circuit (valves V1, V2, V3, V4, V5, V6, V7, V8, V9, V10, V11,V12 respectively) to an individual line sensing relay (VA, VB, VC, VD,VE or VF respectively) which will operate in dependence upon whether theradio, telegraph or telephone circuits con- 3 nected are in use andwhich will in turn operate the appropriate integrating relay RVA, RVB,RVC, RVD, RVE or RVF respectively as follows: The ganged -pole 3-Vposition switch designated RTTS is rotated to the required Vpositiondepending upon the type of circuit sensing re- Audio voltage appliedacross the tip and ring connections of the appropriate circuit jacksV AIis applied to the grid of valve Vla. T heampliiied output of Vla is thenVapplied to thegrid of Vlb and further amplied.

The output of Vlb is then applied across the metal rectifier MRA and theresul-tant D.C. applied to the paralleled grids of V2 thus operatingYthe sensing relay VA,

which in turn will operate its integrating relay RVA.

The integrating relays have a slow to release feature of 2 or 3 secondsso that momentary pauses in speech do not cause it to release andregister a false message count. Thus the extension of speech`transmitted or received over a particular radio circuit connected viathe radio equipment monitor jack, plug and cord connected to theappropriate circuit jack AI, Bl, Cl, DI, El, on FJ of this unit, willoperate the appropriate'line sensing relay VA, VB, VC, VD, VE or VF inthe amplifier detector circuit and this will in turn operate thecorresponding integrating relay. Alternatively, the appropriateintegrating relay can be operated directly by D C. techniques, i.e.earth being extended to it from a relay already having a function in theradio line termination equipment such as from the operation of a channelcall light.

POSITION Z--TELEGLKAPH Upon receipt of the voltage signal elements viathe tip connection of the appropriate circuit jack AJ, the

Vgrids of valve V2 are driven positive above cut-0E and thus operate thesensing relay VA, which in turn via VAI will operate its integratingrelay RVA. As in the case of radio sensing relay RVA has a slow torelease feature such that momentary pausing in the telegraph messagetransmission does not cause it to release and register a false messagecount.

Thus the normal condition of a telegraph circuit which is not in use isa negative potential applied to the grid of V2 (V4, V6, V8, V10, V12 asappropriate) this biassing the valve to cut-oit, hence relay VA (or VB,VC, VD, VE or VF as appropriate), does not operate. However, one or morepositive elements will occur with eac-h character transmitted orreceived when the circuit is in use and this condition will operate inthe amplifier detector circuit the appropriate line sensing relay VA,VB, VC, VD, VE, or VF which may conveniently be of the polarised typeand which in turn operates the corresponding integrating relay whichwill remain operated for Vas long as characters are being transmitted,i.e. for as long as the circuit is in use, and for a further shortperiod, if desired, to ensure continuity of record of each message. ItWill be noted that under telegraph conditions valves V2, V4, V6, V8, Vand V12 only are used.

POSITION Iii-TELEPHONE Under -free line conditions P.B.X batterynegative potential exlsts on the sleeve connection of the circuit kjackAI Vthis effectively short circuits the sensing relay RVA remains unopVthe sensing relay VA operates to the resistance earth extended viathesleeve connection of the P.B.X operators Vcard circuit used toestablish the engaged Condition and vr2,991,935 Y' Y f e to the negativeterminal of the telephone switchboard battery connection shown in FIGURE7. Relay RVA hence operates via VAl but in this case the integratingrelay RVA has no slow to release feature since it opcrates as a singlecoil relay, its secondary winding being open circuit. v p Y Thus theinsertion of a plug having sleeve connection only and being physicallydevoid of tip and ring connections in a circuit appearance jack Of theswitchboard multiple of the line of the telephone circuit underinvestigation will, when that circuit is brought into use, i.e. when ithas a cord circuit plug connection at any of its other parallel jackappearances on the switchboard, extend a different potential from itsidle condition over the sleeve connection of the cord connection AI, BI,Cl, DI, E] or F] of this equipment (FIGURE l) to operate the appropriateline sensing relay VA, VB, VC, VD, VEjor VF in the amplifier detectorcircuit which will operate the appropriate integrating relay of RVA toRVF which will remain operated for as long as the circuit is in use,i.e. has a plug inserted in one of its parallel appearance Vjacks of theswitchboard. It may be convenient in checking the utilization in P.B.Xtelephone circuits to use the same battery for sensing purposes as thatfrom which the P.B.X itself derives its power. FIGURE 1 shows connectionto the P.B.X battery via exchange terminal Six counters which mayconveniently have five digits, designated LCM1-LCM6 will record thecircuit utilization time in seconds for the period under investigation.

Six counters which may conveniently be of four digits,

designated LCM7-LCM12 will record the total number of messages orcontinuous periods of utilization completed over each signal channelduring the period of investigation. Y

A D.C. buzzer designated B which may be brought into operation upon therecording of circuit utilization of any of the circuits underinvestigation.

Six locking plunger-type keys designated LKA to LKF when depressedmanually permit buzzer B to sound when the appropriate circuit is inuse.

Six lamp jacks designated A which circuit is in use.

Circuit description If the electromagnetic counters LCM are not of thereset-digit pattern it will be necessary to note the number registeredon each counter before their commencement of operation.

'I'he line sensing relay associated with the ampliiier detector circuitof the jack designated circuit jack A] is itself designated relay VA,likewise circuit jacks BI, CJ, DI E] and FI have line sensing relays VB,VC, VD, VE, VF connected via their corresponding amplifier detectorcircuits. i

To describe a typical circuit operation on circuit A only: 'Theoperation of the battery on/ oi switch to the On position completes theinherent one-second pulse circuit of relay TP and causes relay TP topulse operate at one-second intervals via earth extended from P2 viapulse pack PI, without a plug inserted. Battery pulse lamp BPL will alsopulse operate in sympathy with it at TPI in its non-operated position. Y

Conversely, in its operated position TPI extends pulsing earth atone-second intervals via RVAl which is operated only when the circuitconnected'to circuit jack AJ is in use, and pulse operates the livedigit counter LCMI to register the circuit utilization in seconds. Earthfrom RVAZ also operates circuit A lamp to indicate that the circuit isVbusy. Relay HA is slow to Vrelease and thus upon the release of relay,RVA, i.e. upon the termito F which will indicate Vnation of circuit use,permits Vearthivia RVAZ, HAI to step counter LCM7 one digit to registertheV completion ofthe message.

(Similarly the message count feature Yusing'circuitB is effected withthe slow release feature of relay HB Whi)ch operates from earth extendedfrom RVBZ and so on.

It follows that when relay VA is released .e. when the circuit is notutilised, no further count will be registered on LCM1 counter.

The pulsing contact TP1 on the other hand is pulsing irrespective ofwhether the circuit is being utilised or not.

When it is desired to terminate the utilization and/or message countcheck the operation of the battery on/oif switch to the olf positionwill prevent further counting and the counter registrations may then betranscribed.

UTILIZATION ALARM Depression of the locking type plunger key LKA whencircuit A is being monitored permits the operation of the buzzer to beeifected via RVA3 when the circuit is in use. The buzzer may be silencedby operating the key LKA to its extended position. Similarly operationof LKB to LKF will control the alarm of circuits B to F respectively.

In FIGURES 2 and 2a six counters, which may conveniently be of thefive-digit type, designated LCM1 to LCM6 adapted to have type head orembossed figure characters which will record the circuit utilizationtime in seconds (or any other desired period of time).

Six counters, which may conveniently be of the fourdigit type,designated LCM7 to LCM'lZ which will record the total number of messagescompleted over each signal channel during the period of investigation.

Six counters, which may conveniently be of the fourdigit type capable ofbeing electromagnetically reset, designated LCMIS-LCMIS which willrecord the length of time in seconds (or any other desired period oftime) of each message.

Six ratchet or other drive-operated rolls of paper or other means ofpermanent record which are positioned to traverse the surface of eachgroup of three counters (for example in the case of circuit A the threecounters would be LCM1, LCM7, LCM13).

Six drive magnets designated MCADM, MCBDM, MCCDM, MCDDM, MCEDM andMCF'DM which will operate simultaneously via contacts of PR relay (PRZto PR7) which is operated when the period count, as determined by theposition of PSS (FIGURE 5 or 6) has been completed. MCADM to MCFDMdepress the type head or embossed figure characters of the paper rollpassing over VVthe faces of the (four-digit) counters LCM7 to LCM12 andthe (five-digit) counters LCM1 to LCM6 to record the circuit utilizationtime of each of the six (tive-digit) counters and the total number ofmessages received on each of the six (flow-digit) counters associatedwith the six circuits A to F in speci-tic intervals of time asdetermined by the setting of switch PSS (FIG- URE 3 or 4).

Six drive magnets PMADM, PMBDM, PMCDM, PMDDM, PMEDM and PMGDM which whenoperated depress the type head or embossed igure characters of the paperroll passing over the face of the (four digit resettable) counters LCM13-to LCMIS to record the length of each message. These drive magnets areoperated via MA1, MB1, MC1, MD1, MB1, and MF1 respectively Iat thecompletion of each message via the slow release of relay HA to HFrespectively as previously described.

'I'he release of each of these twelve drive magnets causes the paper orother material line feed to be advanced one step ready for the nextprinting or record.

The additional third utilization (four-digit) resettable counters LCM13to LCM18 may conveniently be arranged to reset after each recording atthe end of each message. This counter reset mechanism would beelectromagnetic and would derive operation on the release of relays HAto HF.

Six relays designated MA to MF are operated simultaneously with theoperation of the message counters LCM7-LCM12 which in turn, via theircontacts MA1 6 to MF1 operate drive magnets PMADM to PMFDM respectively.

Non-locking plunger type key RK may be depressed when it is desired toreset the counting unit of FIGURE 5 or 6.

A typical printed record of the meters LCM1, LCM7 and LCM13 is given inthe following table:

A B O Occurrence (on (on (on LCM1) LCM7) LCM13) Analysis check commencesat 0800 hrs. A and B would not normally be at zero, .e. not beingresettable from previous operation) 00, 000 0, 000 O, 000 Messageoccurs. 18secs. 18 Message occurs. 36 secs 36 Message occurs. 1 min. 24sec 84 X. First count period ends. (0805 hrs 3 Message occurs 2 min. 54secs 174 Message occurs 1 min. 33 secs 93 Message occurs 3 mins. 10secs. starting 30 seconds before end of second count period X. Secondcount per nds (0810 hrs.).

Message ends Message occurs 1 min. 57 secs Message occurs 24 secs X.Third count period ends (0815 hrs.)

Message commences 1 min. after start of fourth count period for 12 min.10 secs.

X. Fourth count period ends (0820 hrs.)

X. Fifth count period ends (0825 hrs.)

Long message ends (3 min. l0 secs. after start of period) X. Sixth countperiod ends (0830 hrs.).

X. Seventh count period ends no messages (0835 hrs.)

and so on.

The actual mounting of these three meters in a suitable installationwill be apparent from FIGURES 3 and 4. Thus sprocket hole edged paperfrom a roll 2 is fed over sprocket 3 and down in front of the threemeters 4 between a pressure pad 5 and the printing wheels 6 of themeters. Then the paper passes over a lower sprocket 7 and away to awind-up roll 8.

The three meters 4 `are mounted side by side in dependent reciprocationin the direction of their lengths by solenoids 9 and restoring springs10. The solenoids 9 also advance the sprockets 7 in their operation.

Each meter when it is operated by its associated solenoid pulls itsprinting wheels 6 up to the pressure pad 5 and thereby prints thefigures to be recorded on to the paper.

In FIGURE 5 there is shown four cycling selector switches M, C, D, and Uwhich with suitable strapping of their bank contacts M4, C4, D4 and U4to particular outlets of a Period Selection Switch PSS1 to PSS4 permitthe counting of any successive series of one-second pulses before theoperation of relay PR (FIGURE 2a).

The nine-position switch PSS designated period selection switch has fourpoles designated PSS1 to PSS4 each having six pre-set count periods oftive minutes, ten minutes, iifteen minutes, thirty minutes, one hourlyand two hourly periods with the addition of three further positions towhich any particular count period may be pre-set to meet particularrequirements.

The pulsing contact TP1 is pulsing drive magnet UDM irrespective ofwhether the circuit is being utilized or not.

When uniselector U steps to bank contact 11, .e. upon completion of thetenth one-second pulse, earth is extended from the wipers of arc U3 togive a single earth pulse to operate drive magnet DDM. Uniselector Uself-drives via its own interrupter springs Udm to earth from bankcontacts 11, 12 and 13 of arc U1 to bank contact 14.

Drive magnet DDM remains operated whilst uniselector U steps over bankcontacts 111 and 12 since the wipers of uniselector U are of thebridging type and-contact two adjacent bank contacts simultaneously.

When the wipers of uniselector U reach bank Contact 113, drive magnetDDM is de-energised and hence the Wipers of uniselector D step to bankcontact Z.

I Uniselector U steps to bank contact 14 which incommon with its bankcontact 1 is a home position due to the strapping of bank contacts ingroups such that every halfrevolution of its wipersr will permit twentyseconds to be counted. The cycle of events is then repeated. A

1 further ten one-second pulses are then received and counted.

Uniselector D is stepped to bank contact`3 to indicate a count of twentyseconds. This progression of events will continue until ninety-nineseconds have been counted.

Upon completion of the hundredth one-second pulse, however, uniselectorU will operate, as previously described, and uniselector D willrstep toits eleventh bankY contact when an earth pulse will-be extended via theWipers of arc D3 bank contact 11 to energise drive magn net CDM.

Uniselector D selffdrives via its oWn interrupter springs Ddm to earthfrom bank contacts 11, 12 and 13 of arc D1 to bank contact 14. When thewipers of uniselector -f D reach'bank contact 13, drive magnet CDM willbe deenergised to step unis'elector C to bank contact 2.

The progression of events continues until nine hundred "and'ninety-nineseconds have been counted.

Upon completion of the Ithousandth one-second pulse, however, the wipersof uniselector C will step to their eleventh bank contact and willextend an earth pulse to i energize drive magnet MDM. When theV wipersof uni- Selector C reach bank contact 13, drive magnet MDM l willvbede-cnergised thus permitting the wipers of uniselector to stepto bankcontact 2, i.e. one thousand one-second pulses have been counted.

- If, for example, the period sequence time interval is 'hourly, i.e.three thousand six hundred seconds are required to be counted, theprogression of count proceeds as described.

e' On completion of the three thousand six hundredth one-second pulse,however, earth is extended via the period selection'switch PSS4 pre-setto position 6, the one 'hourly count period, the wiper of arc M4 bankcontact -4 `via the period selection switch PSS3 preset to posi- "tion,the wiper of uniselector `arc C4 bank contact 7 via period selectionswitch PSSZ 5 preset `tofposition 6 to the wiper of arc D4 bank contact1 to PSS1 preset to position 6, to the wiper of arc U4 bank contact-1 tooperate relay S via its operate coil and also "extends earth to operaterelay PR (FIGURE 2a). S1 holds relay S via earth extended from arcs U2,D2, C2 and M2 in parallel and also completes the circuit for theself-drive of uniselector U via arc U1 to step it to its' 'home contact(bank contact 1 or 14 as appropriate). Likewise, earth extended via S2,S3 and S4 permits uni- Vselectors D, C and M respectively to self-driveto theirv home contacts 1 or 14 as appropriate. The earth extended viathe period selection switch PSS1-P854 preset to position 6 via arcs M4,C4, D4 and nU4'is Vremoved and permits relay PR to release. Im-,mediately these uniselectors commence to home. Simultaneously earth isremoved from the operate coil of relay S which releases whenuniselectors U, D, C and M have Y reached their home contacts 1 or 14 asappropriate. Contacts PRZ to PR7 (FIGURE 2a) operate the appropri- `atedrive magnet of MCADM to MCFDM to depress the 'Il paper ,roll or othermeans of record on to LCM-1 to LCM6 and LCM7 to LCM12 counters tovrecord their registrations, The circuit utilization count for the secondt count period,i.e. of the second hour of the example being 8 described,then proceeds in similar fashion cooperate the electromagnetic printingcontrol at the end of the next hourly count period (i.e. a further 3,600seconds).

The speed with which uniselectiors U, D, C *and M self-drive to theirhome contacts'will ensure that they are reached before the initialone-second pulse of the second count period is elected.

The counter unit (FIGURE 3) proceeds to count three thousand'six hundredseconds as before.

This hourly cycle of events continues indeiinitely. In FIGURE 6 there isshown two ten-step ratchet relays and

which are of the forward action type, i.e. the cams'rotate one ratchettooth upon the energising of the drive magnets. Ratchet relay steps oneratchet tooth for each one-second pulse and ratchet relay Y periodselection switch having six pre-set count periods of ve .minuten tenminutes, fifteen minutes, thirty minutes, one hourly and two hourlyperiods with the addition of three further positions to which anyparticular count period may be pre-set to meet particular requirements.

A typical operation on the circuit connected to circuit jack AJ ofFIGURE 2 only and using the period selection unit and counter of FIGURE5 will be-described:

The one-second pulse relay TP (FIGURE 2) is pulsing at one-secondintervals inefectively at this stage apart lfrom indicating that it isreceiving the incoming pulses from the inherent one-second pulse circuitor from an external pulse connected by plug and cord connection to theone-second pulse jack PJ. It will be noted that if the latter source ofpulse is used the insertion of the plug will disconnect the inherentpulsing circuit and render it ineffective.

The battery pulse lamp BPL is pulse operating at onesecond intervals viaearth from the pulsing contact TPZ in its released position.

Upon receipt of the first one-second pulse, relay AB receipt of thetenth one-secondl pulse.

AB1 prepares the circuit for the extension of earth via operate theten-step ratchet drive magnet DDM on receipt of the tenth one-secondpulse effected upon the slow release of relay AB.

Relay AC operates upon receipt of the tenth one-second pulse via earthextended from D1 cam springset operated,

SS4 norm-al and will remain operated untilV receipt-of the one hundredthone-second pulse. AC1 prepares the drive magnet CDM which will step itswipers on to their second bank contact upon the release of relay ACwhich is effected by the D1 cam springset operating on its tenth stepi.e. on receipt of the hundredth one-second pulse.

It will be appreciated that relay AC has a slow to release feature onlywhen relay SS is normal since earth via SS2 short circuits itssubsidiary coils. Under reset conditions to be described later the verymuch shorter release lag of this relay when S82 is operated effects thehoming of the 2 and drive magnets in as short a time as possible.

The slow to release feature of relays AB and AC also permit adequatelength of pulse to be extended to drive magnet DDM land drive magnet CDMrespectively every time a tenth and/ or hundredth pulse is registered.

This progression of events will continue until nine hundred andninety-nine seconds have been counted. Upon completion of the thousandthone-second pulse, however, drive magnet CDM is pulse operated andextends earth via C3 wiper bank contact 11 to energize drive magnet MDMwhich will permit Uniselector wipers to step to their second bankcontacts when the wipers of Uniselector have stepped to their thirteenthbank contact.

Uniselector wipers to their seventh bank contact (upon completion of thethree thousand six hundredth one-second pulse).

Earth is then extended to operate relay S. It will be notedthat no unitsor tens digits are to be counted and at this particular moment both theratchet relays are in their home position.

Earth is also extended to operate relay PR which via its contacts PRZ toPR7 (FIGURE 2a) operate the 'appropriate drive magnet of MCADM to MCFDMto depress the type head or embossed figures or actuate the other meansof record to register the count of LCM1 to LCM6 and LCM7 to LCM12.

S1 `holds relay S via earth extended from arc C2 and arc M2 in parallel.

S1 also completes the circuit for the self-drive of uniselector C viaarc C1 to step to its home contact (bank contact 1 or 14 asappropriate). Likewise earths are extended via S2 to home uniselector Mto its home circuit 1 or 14 as appropriate.

The homing of uniselectors C and M removes the earth via the periodselection switch 1, position 6, from the initial operate coil of relayS.

When uniselectors C and M are on their home contact 1 or 14, asappropriate, earth is removed from arc C2 and arc M2 respectively thuspermitting .the relay S to release.

All other facilities are identical with described.

The circuit facilities above described have taken as the example a onehour count period, i.e. three 4thousand six hundred seconds have beencounted, before the uniselector steps to its ynext bank contact tocommence the second count period. However, it will be seen that theperiod selection switch PSS (FIGURES 4 and 5) is of nine positions andthat any of the following six count periods may be selected.

Position Z-ve minute periods (three hundred seconds) Position 3-tenminute periods (six hundred seconds) Position 4-fteen minute periods(nine hundred seconds) Position 5thirty minute periods (eighteen hundredseconds) Position 6-one hour periods (three thousand six hundredseconds) Position 7-two hour periods (seven thousand two hundredseconds) Positions 1, 8 and 9 have not been wired and will permit vachoice of any three additional count periods to be effected by simplewiring on the banks of the counting unit uniselectors (FIGURES 5 'and 6as appropriate).

It should be noted that whilst the foregoing description has assumed theuse of a counting circuit employing uniselectors from which the periodpulse from live minutes to two hours or any other period of time isderived, this may also be achieved conveniently from a synand thosepreviously chronous motor operated from an A C. mains supply having camoperated spring sets which could be selected or preset to operate at anydesired period. Likewise, the one-second pulse source could be derivedfrom a synchronous motor controlling a cam operated springset.

In FIGURES 7 and 7a there is shown a cycling selector switch PSdesignated period sequence switch connected to a total number ofseventy-two four-digit electromagnetic counters designated LCM1 andLCM72.

Terminals BT are designated battery terminals and to these connection ismade by plug and cord connection to a fty volt and volt DtC. source ofsupply, the negative terminals of which are commoned to earth.

A jack P] is designated one-second pulse jack to which connection ismade by plug and cord connection to a second D.C. pulse source of supplyif `derived from a master clock system.

The lamp BPL is designated battery and pulse lamp to indicate that thebattery is connected and that the equipment is receiving the train ofincoming one-second l. nection is made by Yplug and `cord connection tothe( equipment monitor jacks of the circuts under investigation. Each ofthese circuit jacks is Yconnected .via an yampliiier detector circuit toan individual line sensing relay (VA, VB, VC, YVD, VE, orY VFrespectively), which will operate independence upon whether radio,telegraph or telephone circuits are to be monitored and which will inturn operate the appropriate integrating relay VRVA, RVB, RVC, RVD, RVEor RVF respectively Y as follows.

The gang/ed -pole 3-position switchcdesignated R'ITS Y is rotatedYtotherequired position depending upon the type of circuit sensingrequired for a particular analysis. This positionY l` provides for radio(speech) sensing,

l position 2 for telegraph (circuit) sensing and position 3 fortelephone circuit (PBX terminated) sensing.

A typical operation on circuit A only of this sensing unit under thethree conditions'referred to above is as follows: I A

lPOSITION l--RADIO Audio voltage applied across the tip and ringconnections of the appropriate circuit jacks AJ is applied to of 2 or 3seconds so that momentary pauses in speech do not cause it to releaseand register a false message count.

Thus the extension of speech transmitted or received over a particularradio circuit connected via the radio equipment monitor jack, plug andcord connected to the appropriate circuit jack AJ, BI, CJ, DI, El or FIof this unit will operate the appropriate line sensing relay VA, VB, VC,VD, VE or VF in the ampliiier detector circuit and this will in turnoperate the corresponding integrating relay which willremain operatedfor as long as speech is maintained and for `a short period,`approximately two to three seconds after speech is terminated whichwill ensure that short pauses in speech are recorded as continuousutilisation. Alternatively, the appropriate integrating relay can beoperated directly by D C. techniques, i.e. earth being extended to itfrom a relay already having a function in the radio line terminationequipment such as from the operation of a channel call light.

POSITION Z-TELEGRAPH Upon receipt of the voltage signal elements via thetip connection of the appropriate circuit jack AJ, the grids of valve V2are driven positive above cut-ot and thus operate the sensing relay VA,which in turn via VAI will operate its integrating relay RVA. As in thecase of radio sensing relay RVA has a slow to release feature such thatmomentary pausing in the telegraph message transmission does not causeit to release and register a false message count. Y

Thus the normal condition to the line sensing relay when the circuit isnot in use is a negative eighty volts condition. However, one or morepositive elements (positive eighty volts) will occur with each charactertransmitted or received when the circuit is in use and this conditionwill operate in the amplifrer detector circuit the appropriate linesensing relay VA, VB, VC, VD, V\E

or VF which may conveniently be of the polarised type and which in turnoperates the'corresponding integrating relay which will remain operatedfor las long Vas l2 characters are being transmitted i.e. for as long asthe circuit is in use, and for a further short period, if desired, toensure continuity of record of each message, it will be noted that undertelegraph conditions valves V2, V4, V6, V8, V10 and V12 only are used.

PosrrroN 3 TELEPHONE Under free `line conditions P.B.X battery negativepotential exists on the sleeve connection of the circuit jack Al, thiseiectively short circuits the sensing relay VA and thus the integratingrelay RVA remains unoperated.

However, when the circuit under analysis is engaged the sensing relay VAoperates on the resistance earth extended via the sleeve connection ofthe PBX operators card circuit used to establish the engaged condition,and to the negative terminalY of the telephone switchboard batteryconnection shown in FIGURE 7. Relay RVA hence operates Via VAl but inthis case the integrating relay RVA has no slow to release feature sinceit operates as a single coil relay, its secondary winding being opencircuit.

Thus the insertion of a plug having sleeve connection only and beingphysically devoid of tip and ring connections in a circuit appearancejack of the switchboard of the line of the telephone circuit underinvestigation will, when that circuit is brought into use, i.e. when ithas a plug and cord connection at any of its other parallel jackappearances on the switchboard, extend a diierent potential from itsidle condition over the sleeve connection of the cord connection Al, BJ,CI, Dl, El or FI of this equipment (FIGURE l) to operate the appropri-`ate integrating relay RVA, RVB, RVC, RVD, RVE or RVF in the amplifierdetector circuit which will remain operated for as long as the circuitis in use, i.e. has a plug inserted in one of its parallel appearancejacks of the switchboard.

A three position switch CCS designated circuit selection switch havingseven poles designated CCSl to CCS7 will give the following facilities:

Position 1 .-TIzree circuits monitored (Normally the circuits connectedvia plug and cord connections to circuit jacks A, B and C). This willpermit a circuit utilisation count and number of messages count overtwelve periods simultaneously for each circuit connected.

Position 2.-Three circuits monitored (Normally the circuits connectedvia plug and cord connections to circuit jacks A, B and C). This willpermit a circuit utilization count over twenty-four periodssimultaneously for each circuit connected.

Position 3.-Six circuits monitored Connected via plug and cordconnections to circuit jacks A, B, C, D, E and F). This will permit acircuit p utilization count over twelve periods simultaneously for eachcircuit. c

A jack CAI designated camera jack, if desired, may -be connected viaplug and cord connection to an electrically actuated shutter mechanismof a camera to photograph thercounter registration at the completion ofa particular count period cycle. This would be of particular use undercontinuous operation conditions.

A two position switch CCOS designated 12/24 count/ continuous operationwhich is operated depending on whether (a) a specific period count oftwelve or twentyfour count periods is required or (b) it is required toefr fect a continuous monitoring of the circuits in questionindefinitely until manually stopped.

An alarm circuit designated record alarm consisting of a lamp L andbuzzer B which will be brought into operation under continuous operationconditions and which will, on the commencement of the twelfth andtwentyfourth count period as appropriate, operate the lamp L and buzzerB to draw attention to the fact that the first eleven or twenty-threecounts, as appropriate, as registered on the counters should now benoted. It will similarly operate on the completion of the twelfth andtwentyfourth count period as appropriate to ensure that the counts onthe twelfth or twenty-fourth counters are then noted.

A locking plunger type key designated record alarm key RAK which whenextended will extinguish the record alarm lamp L and silence the buzzerB under the first conditions as in the preceding paragraph i.e. at thecommencement of the twelfth or twenty-fourth count period, asappropriate. When the twelfth or twenty-fourth count period, asappropriate, has been completed the period sequence switch PS will stepautomatically (under continuous operation conditions) to the iirst setof counters connected again the record alarm lamp L and buzzer B willoperate to indicate that the twelfth and twenty-fourth count period, asappropraite, has been completed and that the count as indicated on thetwelfth or twenty-fourth counters should now be noted. The operation ofthe record alarm key RAK depressed to its original postion willextinguish the lamp L and silence the buzzer B and will be ready tooperate upon the commencement of the twenty-fourth or forty-eighth countperiod, as appropriate. This cycle of events will continue untilmanually stopped either by the operation of the continuous operationswitch CCOS to the 12/24 count position or by operation of the batteryswitch to its Off position.

A lamp jack RL designated reset lamp (FIGURE which will indicate thatthe cycling selector switch period sequence switch PS is on its homecontact and is ready to start sequence of count periods.

A non-locking plunger type key SRK designated start/ reset `key whichwhen momentarily depressed with the reset lamp RL operated starts theperiod count cycle. If the reset lamp RL is not operated, momentarydepression of this key will Ireturn the cycling selector switch periodsequence switch PS to its first contact to permit the reset lamp RL tooperate.

CIRCUIT DESCRIPTION NOTE-If the seventy-two four-digit electromagneticcounters LCM are not of the reset digit pattern it will be necessary tonote the number registered on each counter before their commencement ofoperation.

The line sensing relay associated with the amplifier detector circuit ofthe jack designated circuit jack AI is itself designated relay VA,likewise circuit jacks BI, CI, DI, EI and FI have line sensing relaysVB, VC, VD, VE, VF connected via their own amplifier detector circuits.

(1) Three circuits monitored-Le. plug and cord connection to circuitjacks AI, BI and CJ for a period count of twelve count periods on each,i.e. the period selection switch PSS of FIGURE 5 preset to the desiredcount period and the circuit selection switch CCS preset to position 1and the 12/24/continuous operation CCOS preset to 12/ 24.

This will permit a circuit utilization count and nurnber of messagescount to be taken over twelve count periods for each of the threecircuits connected to the circuit jacks AJ, BJ and CJ.

To describe a typical circuit operation on circuit A only with theperiod selection switch preset to position 6, i.e. the hourly countperiod. 'The one-second pulse relay TP is pulsing at one-secondintervals ineffectively at this stage apart from indicating that it isreceiving the incoming pulses from the inherent one-second pulse circuitor from an external master clock connection i.e. the battery and pulselamp BPL is pulse operating at one second intervals via earth and thepulsing contact TPZ is in its unoperated normal position.

Momentary depression of the non-locking type plunger 14 key start/resetkey SRK (FIGURE 7) will extend earth momentarily to operate the yperiodsequence switch drive magnet PSDM which will cause its associated wipersto step to their bank contacts 2 upon release of the key.

Relay G operates via arc PS1 to battery via drive magnet PSDM and relaySS in parallel, neither `of these operates in series with relay G sincethis latter is of higher resistance.

G1 (FIGURE 5) operates and extinguishes the reset lamp RL and completesthe circuit for the extension of earth condition via TP1 (the one-secondpulsing contact) to pulse the units uniselector drive magnet UDM, thewipers of which will traverse their bank contacts one contact persecond.

'IPZ (FIGURE 7a) extends pulsing earth at one-second intervals via RVAlwhich is operated only when the circuit connected to circuit jack A] isin use and pulse operates the four-digit counter LCM1 via arc PS5 bankcontact 2 to register the circuit utilization in seconds during thefirst hourly count period. Earth from RVA2 also operates circuit A lampto indicate that the circuit is busy. Relay HA is slow to release andthus upon the release of relay RVA, viz, upon the termination ofconversation, permits earth via RVAl, HAI, position 1 of CCS4, arc PS4bank contact 2 to step counter LCM13 one digit to register thecompletion of one message during the irst hourly count period.(Similarly the message count feature using circuit B is eifected withthe slow release feature of relay HB which operates from earth extendedfrom RVB12.)

It follows that when relay VA is released, i.e. when the circuit is notutilized no further count will be registered on LCM1 counter.

The pulsing Contact TP1 on the other hand is pulsing drive magnet UDMirrespective of whether the circuit is being utilized or not.

When uniselector U steps to bank contact 11, i.e. upon completion of thetenth one-second pulse, earth is extended from the wipers of arc U3 togive a single earth pulse to operate drive magnet DDM. Uniselector Uselfdrives via its own interrupter springs Udm to earth from bankcontacts 11, 12 and 13 of arc U1 to bank contact 14.

Drive magnet DDM remains operated whilst uniselector U steps over bankcontacts 11 and 12 since the wipers of uniselector U are of the bridgingtype and contact two adjacent bank contacts simultaneously.

When the wipers of uniselector U reach bank contact 13, drive magnet DDMis de-energised and hence the wipers of uniselector D step to bankcontact 2.

Uniselector U steps to bank contact 14 which in common with its bankcontact 1 is a home position due to the strapping of bank contacts ingroups such that every half revolution of its wipers will permit twentyseconds to be counted. The cycle of events is then repeated. A furtherten one-second pulses are then received and counted.

Uniselector D is stepped to bank contact 3 to indicate a count of twentyseconds. This progression of events will continue until ninety-nineseconds have been counted,

Upon completion of the hundredth one-second pulse, however, uniselectorU will operate, as previously described and uniselector D will step toits eleventh bank contact when an earth pulse will be extended via thewipers of arc D3 bank contact 11 to energise drive magnet CDM.

Uniselector D self-drives via its own interrupter springs Ddm to earthfrom bank contacts 11, 12 and 13 of arc D1 to bank contact 14. When thewipers of uniselector wipers Vto their fourteenth bankcontact.1vextended via PS1 bank contacts 14 to 25 strapped from 70 CCS preset toposition l,

`15 YD reach bankV contact 3, drive magnet VCDM will be deenergised tostep uniselector C to bank contact 2.

'Ihe progression of events continues until nine hundred and ninety-nineseconds have been counted.

Upon completion of the thousandth one-second pulse,

however, the wipers of uniselector C will step to Ytheir eleventh bankcontact and will extendY an learth pulse to energise driveY magnet MDM.When the wipers of uniselector C reach bank contact 13, drive magnet MDMwill be deenergised thus permitting'the wipers of uniselector to steptobank contact 2, i.e. one thousand one-second pulses have been counted.

In the example taken the period sequence time interval is hourly, i.e.three thousand six hundred seconds are required to -be counted. Theprogression of count proceeds as previously described. s Y

' On completion ofthe three thousand six hundredth one-second pulse,however, earth is extended via the period selection Switch PSS4 presettoposition 6, the one hourly count period, the wiper of arc M4 bankContact 4 via f the period selection switch PSS3 preset to position 6,the

wiper of uniselector y arc C4 bank contact 7 via period selectionYswitch PSSZ Y preset to position 6 to the wiper of arc D4 bank, contactl 1 to PSS1 preset to position 6, to the wiper of arc U4 bank contact 1to operate relayV S via its operate coil and Y also extends earth toenergise drive magnet` PSDM (FIG- URE Sfz). S1 holds relay S Via earthextended from arcs U2, D2, C2 and M2 in parallel and alsocompletes thecircuit for the self-drive of uniselector U via arc U1 to step it to itshome contact (bank contact 1 or 14 aS appropriate). Likewise, earthextended via S2, S3 and S4 permits uniselectors D, C' and M respectivelyto selfdrive to their home contacts 1 or 14 as appropriate.

' "The 'earth extended via theperiod selection switch VPSS1-PSS4, presetto position 6, via arcs M4, C4, D4, and U4 is removed from drive magnetPSDM (FIGURE 7a) immediately theseuniselectors commence to home therebyde-energising drive magnet PSDM and stepping the wipers of arcs PS1 toPS8 to their third bank contacts. Simultaneously earth is removed fromthe operate coil of relay S which releases when uniselectors U, D,

. C and M have reached their home contacts 1 or 14 as appropriate.

The circuit utilization count for the' second count period,

' i.e. of .the second hour ofthe example being described, then proceedsin similar fashion to operate counter LCMZ.

. The speed with which uniselectors U, D', C and M selfdrive to theirhome contacts will ensure that they are reached before theV initialone-second pulse of the second 'count' period is effected. Y p

The counter unit (FIGURE proceeds to count thousand six hundred secondsas before; i "Y This hounly cycle of events continues throughout thetwelve hour period count; Upon completion of the twelfth hourly countperiod, earth is extended as before to operate drive magnet PSDM viaarcsM4, C4, D4, and

" U4 in series Via earth extended from the period selection threeswitch'PSSlt, preset to position 6, which on the homing of thecounting'uniselectors M, C, D and U will step Y Earth is then toself-drive uniselector `drivernragnet PSDMr` to its taken.

i '16 Relay G will then release and lin releasing will disconnect thepulsing earth from drive magnet UDM (FIG- VURE 5) and will also operatethe reset lamp RL.

The Vcircuit'analysis in theexample taken has now been completed and thecounter readings may now be If non-resettable counters are in use thenthe respective differences between the totals now registered and thosepreviously noted for each counter will represent respectively thecircuit utilization in seconds during the hourly count periods and thetotal number of messages for the message count during the hourly countperiods Vand these recordings may be then graphically represented ifdesired.

Further facilities which in no way alter the mode of operation of thecircuit utilizationV counts are later described.

(2) Three circuits monitored-circuit utilization only for twenty-fourcount periods on each circuit-The circuit description is identical withthat already described except that since the circuit selection switchCCS is now preset on position 2 it 'permits a circuit utilization countin seconds of the circuits connected via plug and cord connectionnormally to circuit jacks AI, BJ `and CI.

(3) Up to six circuits monitored-circuit utilization on each for twelvecount periods- The circuit selection switch |CCS is on position 3. Thecircuit description is identical with the utilization feature rstdescribed except that pulsing earth is'now extended from VTF2 via RVAI,RVBI, RBCl, RVDIQRVEl and RVFI Via position 3 of the circuit selectionswitch CCS to register the circuit utilization count in seconds of thesix circuits to operate' successively counters LCMl to LCM12; LCM13 -toLCM24; LCM25 to LCM36; LCM37 to LCM48;ALCM49Vto LCM60; and LCM61 toLCM72 for the circuit utilization of each respectively.

CONTINUOUS OPERATION It will be appreciatedthat if a total period countcycle in excess of twelve or twenty-four count periods is required,additional counters would be necessary, their number beingdependent uponthe total period count. In such circumstances it is desirable that thecounters which had registered -the iirst twelve or twenty-four countperiods would'also register the second cycle of twelve/ twenty-fourcount periods and so on.

This requires an alarm circuit to sound upon the completion of eachVperiod count cycle sothat the number registeredon-thecounters may thenbe recorded. The alarm operates uponthe completion of each cycle. Theunit would also be required to start the second andksubsequent countperiod` cycles immediately upon the completion of the twelfth ortwenty-fourth count period of each period count. Y Y Y .The unit hasbeendesigned with this facility using the 12/24 Ycount/continuous operationswitchCCOS thrown to the continuous operationposition. Where, forexample, the twenty-four period count has been selected/on CCS preset toposition 2 to be repeated indefinitely the home contactpbank contact 1."75

circuit description is as follows: -Y

The period countv proceed-s las described previously untilv arcs PS1 toPS8 wipers step to theVtwenty-fth bank contact i.e. for the commencementof the `twentyv fourth count period. Earth is then extended from thestart reset key SRK normal via the'continuous operation switch CCOS, arcPS2 wiper, bank contact 25, via a second contact of the continuousoperationpswitch CCOS, G2 to operate relay iCN. y

This' earth Yis also'extended via the plunger type locking key recordalarm key RAK (inits depressed position) to operate the record alarmlamp L and buzzer B to battery via the `cameraV jack CAJ to warn thatthe record of the counters, in this instance LOMl to LCM23 and LCM25 toLCM47 and LCM49 to LCM71.

Therecord-alarm lamp L and buzzer B, may be extinguished and silencedrespectively by the extension of l? the record alarm key RAK which, aspreviously stated, is of the locking type.

CNI holds relay CN to earth extended from the continuous operationswitch CCOS and the start/reset key SRK normal. CN2 is not effective atthis stage. Upon completion of the twenty-fourth count perioduniselector Wipers step to their home contact, bank contact 1. CN2 thenextends earth via PS1 bank contact 1 to step the wipers of uniselectorto their second bank contacts to commence the circuit utilization countover the second twenty-four count periods.

Earth is then extended from the continuous operation switch CCOS via arcPS2 bank contact 2 again to operate the record alarm lamp L and buzzer Bvia the record alarm key RAK (in its extended position) to battery fromthe camera jack CAI. This will warn that the count of the twenty-fourthcount period should now be noted from counter LCM24, LCM48 and LCM72.

The record alarm lamp L and buzzer B may be extinguished and silencedrespectively upon the depression ofthe record alarm key RAK.

The alarm circuit is now ready to be brought into operation upon thecompletion of the second twentythird count period. This cycle of eventsis repeated indefinitely.

When it is required to terminate the progression of events the operationof the start/reset key SRK will remove the earth from the hold circuitof relay CN which will then Irelease.

Depression of the start/ reset key SRK will also operate relay SS whichwill hold `from earth extended from SS1 via the bank commoning of arcPS1.

SS1 short circuits relay G which then releases.A SS1 permits uniselectorPS to self-drive via arc PS1 bank commoning and its interrupter springsPSdmi to its home bank contact (contact 1).

SSZ (FIGURE 5) extends earth to operate relay S over its operate coil.S1 holds relay S via earth extended from arc U2, arc C2, arc D2, andIarc M2 in parallel and also with S2, S3 and S4 permit uniselectors U,C, D and M respectively of the counter unit to selfdrive to their homecontacts to resume the count when desired.

Under continuous operation conditions, G2 in releasing prevents there-operation of relay CN over its operate coil when uniselector PSwipers are traversing their twenty-fifth bank contact of arc PS2. WhenPS Wipers reach bank contact 1 relay SS releases SS2 and removes theearth from the operate coil of relay SS thus permit- 18 ting relay S torelease when uniselectors U, C, D and M have self-driven to their homecontact 1 or 14 as appropn'ate.

I claim:

41. An larrangement for recording utilization by means of an electricalpulse drive, comprising two groups of counters, a sequence switchadapted to be connected in succession to pairs of counterssimultaneously, one from each of the two groups, means to detect aparticular utilization, means for connecting the pulse `drive to thesequence switch to operate or not to operate one of the pair of countersconnected thereto once for each pulse of the drive, in accordance withthe utilization indication detected, further means adapted to detecteach uninterrupted period of utilization, means for connecting the pulsedrive to the sequence switch to operate the other of the pair ofcounters connected thereto once for each uninterrupted period ofutilization indication detected `and a counting unit connected to stepthe sequence switch to the next pair of counters after Ia predeterminednumber of pulses have been counted.

2. An arrangement for recording simultaneously a plurality ofutilizations by means of an electrical pulse drive comprising aplurality of pairs of groups of counters, the individual counters ineach group each corresponding with a separate particular utilization, asequence switch adapted to be connected in succession to each pair ofgroups of electromagnetic counters simultaneously, a plurality of meanseach adapted to detect ra. separate one of the particular utilizations,means for connecting the pulse drive to the sequence switch to operateor not to operate each of the counters of one of the groups of the pairof groups connected to the sequence switch in accordance with theutilization indication detected, once for each successive interval oftime determined by the pulse drive, a plurality of lfurther means`adapted to detect each uniterrupted period of one of the particularutilizations, means for connecting the pulse drive to the sequenceswitch to operate each of the counters of the other group of the pair ofgroups' connected to the sequence switch once for each uninterruptedperiod of utilization indication detected and `a counting unit connectedto step lthe sequence switch to the next pair of groups of countersafter a predetermined number of pulses of the pulse drive have beencounted thereby.

References Cited in the file of this patent UNITED STATES PATENTS787,969 Yoder Apr. 25, 1905 1,284,430 Norton Nov. 12, 1918 1,713,276Goechler May 14, 1929 2,207,715 Bumstead July 16, 1940 2,368,761 HoganFeb. 6, 1945 2,469,655 Leathers May l0, 1949 2,678,382 Horn et al. May1=1, 1954

